The present application relates to in-ground barriers comprising sections of sheet piling driven into the ground to form a wall, cofferdam or the like. In particular, the present invention relates to watertight connecting joints between adjacent sections of in-ground sheet piling that form a continuous barrier which restricts the migration of groundwater and other liquids.
Interlocking sections of sheet piling driven into the ground is a popular, cost-effective method for installing barrier walls to prevent the movement of soils and limit groundwater migration. Typical sheet piling sections are made of steel plates and have connectors on the side edges. The sheet piling sections are installed sequentially by interlocking the connectors of adjoining sheet piling sections to form a continuous barrier, However, standard sheet piling barriers are not watertight since the interlocking joints provide a potential flow path for the passage of groundwater and other liquids. Attempts have been made to seal the joints between sections of sheet piling but these attempts have been difficult and expensive to implement and have not always provided a watertight seal.
Previously known methods for forming watertight seals between interlocking sheet piling sections use interlocking mechanisms that form cavities when connected to the adjoining section. After the sheet piling sections are driven into the ground, soil, vegetation and other materials that accumulate in the cavities when the sheet piling sections are driven into the ground are removed and the cavities are then filled with a sealant to form a watertight barrier. These methods encounter several problems that make it time consuming and expensive to form a satisfactory watertight seal. Before the cavities can be filled with a sealant, the materials accumulated in the cavities have to be removed using time consuming and labor intensive methods. However, once the barriers are installed in the ground, it is difficult to insure that all of the materials have been removed from the cavities. If any materials are left in a cavity, the sealant may not completely fill the cavity when it is added and a potential flow path is created for groundwater to pass through the barrier.
Several patents describe specially constructed sheet piling sections with interlocking joints which form a cavity that is filled with a sealing material. U.S. Pat. No. 3,302,412 to Hunsucker discloses interlocking thumb and finger elements which form a cavity between adjacent sheet piling sections that is filled with a sealant. U.S. Pat. No. 5,163,785 to Zanelli et al. employ an interlocking sheet piling mechanism shaped like claws that form a cavity for sealant material. U.S. Pat. No. 5,437,520 to Cherry et al. teach joints between piledriven sheet piles having edge forms which interlock to form two cavities that are filled with a sealant.
Certain other types of prior constructions have been tried, but these constructions have required the cavities to be cleaned out after the sheet piling sections are installed before the sealant material is added. Thus, all prior constructions have the inherent disadvantages common to those above denoted relative to materials accumulated in the cavities formed by the interlocking joints when the sheet piling sections are installed.
Another disadvantage of previously known methods is inherent in the fact that they require specially fabricated sheet piles and cannot use standard sheet piles. Also, the interlocking joints of these specially fabricated sheet piles are easily damaged when installed in the ground, either making it difficult to fill the cavities with the sealant or preventing the joint from being properly sealed. An additional disadvantage specially fabricated sheet piles used in previously known methods is that they cannot easily be disassembled and reused because the interlocking connectors are damaged when the sheet piling sections are removed from the ground.
The present invention discloses a method of sealing the joints between sections of standard sheet piling to provide a continuous barrier to the migration of groundwater. This method can also be used to seal the joints between nonstandard sheet piling sections. Sheet piling sections covered by the present invention include: sheet piling sections made of steel, iron, aluminum, or alloyed metals, double wall sheet piling sections, and preformed sheet piling sections made of cement, concrete, and composite materials.
Sheet piling sections are typically installed by sequentially driving individual sections of sheet piling into the ground. Sheet piling sections are connected to adjacent sheet piling sections by means of interlocking joints on the abutting side edges of the sheet piling sections. The joints so formed are not watertight and barriers formed by these sheet piling sections do not prevent the migration of groundwater. It has been discovered that a watertight seal can be formed by attaching a housing containing a sealant material to a sheet piling section prior to installation.
By various aspects of this invention, one or more of the following or other objectives can be obtained.
It is an object of this invention to provide a method of sealing the joints between sheet piling sections that can be easily and economically implemented with readily available materials. The method uses standard sheet piling sections and sealing materials to form an impermeable seal.
It is a further object of this invention to provide a method for sealing sheet piling sections that can be used with standard sheet piling sections or that can be incorporated into the design of sheet piling sections when they are manufactured.
It is still a further object of this invention to provide a method for sealing sheet piling sections that does not damage the connecting edges of the sheet piling when the sheet piling is removed so that the sheet piling sections can be easily reused.
Another object of this invention is to provide a method for sealing the joints between sheet piling sections with damaged connecting edges that do not tightly interlock with the adjoining sheet piling sections.
A further object of this invention is to provide a method for forming a casing for a test well on either one or both sides of a sheet piling section.
Other aspects, objects, and the several advantages of this invention are apparent to one skilled in the art from a study of this disclosure, the drawings, and the appended claims.
According to the present invention, a housing comprising a removable barrier and containing a sealant material is attached to a sheet piling section parallel to and overlapping the connecting edge prior to installation. After the sheet piling section is installed, the barrier is removed and the sealant material contacts the interlocking joint and the adjacent sheet piling sections to form a watertight seal.
In one embodiment of the invention, a xe2x80x9chydroswellablexe2x80x9d sealant material is used, preferably bentonite. The liquid reagent is preferably added to the xe2x80x9chydroswellablexe2x80x9d sealant material after the housing is attached to the sheet piling section and prior to installation. However, the sealant material can also be hydrated by means of a perforated tube or pipe positioned along the longitudinal axis of the housing after the housing and sheet piling section are installed in the ground and the barrier is removed. The liquid reacts with the sealant material to increase the volume and insure a tight seal around the joint. In another embodiment, a polyurethane foam is injected into the housing under pressure and subsequently solidifies to form a watertight seal. In still another embodiment, a metal tube is placed in the housing extending along its longitudinal axis and plastic, rubber, silicone or other synthetic material in the form of resins or pellets is packed into the housing around the tube. After the sheet piling section and the attached housing have been installed in the ground, the barrier is removed and a heating element is inserted into the tube to heat the sealant material to a temperature above its melting point. After the sealant material has melted, the heating element is withdrawn from the tube and the sealant material solidifies to form a watertight seal.